doudou348131346 2017-09-10 09:25
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如何在Go或python中将struct写入文件?

In C/C++, we can write a struct to file like this:

#include <stdio.h>
struct mystruct
{
    int i;
    char cha;
};

int main(void)
{
    FILE *stream;
    struct mystruct s;
    stream = fopen("TEST.$$$", "wb"))
    s.i = 0;
    s.cha = 'A';
    fwrite(&s, sizeof(s), 1, stream); 
    fclose(stream); 
    return 0;
}

But how to wirte a struct to file in go or python ? I want the data in struct are continuous.

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  • dsfsfsfsfs55656 2017-09-10 09:43
    关注

    In Python you can use ctypes module which allows you to generate structures with similar layout as C does, and convert them to byte arrays:

    import ctypes
    
    class MyStruct(ctypes.Structure):
        _fields_ = [('i', ctypes.c_int),
                    ('cha', ctypes.c_char)]
    
    s = MyStruct()
    s.i = 0
    s.cha = 'A'
    
    f.write(bytearray(s))
    

    There is a simplest approach in Python with using struct.pack and manually provide a layout as first argument ('ic' means int followed by a char):

    import struct 
    f.write(struct.pack('ic', 0, 'A'))
    

    Go can encode structs via encoding/binary

    type myStruct struct {
        i int 
        cha byte
    }
    
    s := myStruct{i: 0, cha:'A'}
    binary.Write(f, binary.LittleEndian, &s)
    

    NOTE: You will be subject of differing structure alignment, padding and endianness, so if you want to build truly interoperable program, use special formats such as Google Protobuf

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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